The present invention relates to a new and improved method for monitoring a predeterminate or predetermined yarn quality of a yarn or the like produced by a textile machine, especially a friction spinning apparatus, and further pertains to a new and improved friction spinning apparatus for performing the inventive method.
In the context of this disclosure, the term "yarn" or equivalent expressions, are used in their broader sense to encompass not only yarns as such, but also threads and other filamentary material.
In the production of yarn, the evenness of the yarn quality at each spinning position or location, as well as the comparative yarn quality between the individual spinning positions or locations, plays an important role.
German Published Patent Application No. 3,517,763 A1, published Nov. 20, 1986, discloses a method and an apparatus for maintaining a predetermined yarn twist to enable checking or controlling the evenness of this yarn quality parameter.
Direct measurement of yarn twist while the spinning process is in progress cannot be achieved. Accordingly, the yarn twist must be estimated with the aid of a yarn diameter measurement. This can be accomplished without contact between the yarn to be measured and the measuring device, i.e. can be measured only indirectly.